Docs: Remove docutils pin

[hugovk]

This reverts commit 9509a73.

Changes proposed in this pull request:

• Undo PR Docs: Temporarily pin docutils to fix bullets in sphinx_rtd_theme #5704 now Sphinx 1.0.0 has been released
• https://github.com/readthedocs/sphinx_rtd_theme/releases/tag/1.0.0
• https://github.com/readthedocs/sphinx_rtd_theme/tags

[hugovk]

First build still missing bullet points:

https://pillow--5821.org.readthedocs.build/en/5821/releasenotes/8.3.2.html

Because it's still installing the old one:

Collecting sphinx-rtd-theme<0.5
  Downloading sphinx_rtd_theme-0.4.3-py2.py3-none-any.whl (6.4 MB)

https://readthedocs.org/api/v2/build/15217187.txt
https://readthedocs.org/projects/pillow/builds/15217187/

Need to update this.

[hugovk]

There we go!

[nulano]

And there is a fresh new look for functions!

(although the "Parameters:" title could use a bit of padding-right)

Old version for comparison:

[radarhere]

Thanks!